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UNITED STATES PATENT FFICE.

WALTER J. MILLER, OF ST. PAUL, MINNESOTA.

DYE COMPOUND.

No Drawing.

To all whom it may concern Be it known that I, WAL'rnn J MILLER, a citizen of the United States, residing at St.

.Paul, in the county of Ramsey and State of -part of pyroligneous acid or crude wood vinegar, 1 part of extract of logwood or heematein crystals, 64% parts of water and .00625 part of anilin nigrosin.

The first four ingredients named are first dissolved separately in water at one hundred and fifty degrees Fahrenheit, the sixty-four parts of water being divided into four equal parts for that purpose. The four solutions are then mixed and stirred well. The haematein crystals and nigrosin are then added and the solution allowed to stand from eight to ten hours. The pyroligneous acid is then added, the liquid being well stirred before using. This liquid colors materials a bluish blooming black. This compound when mixed is a mixture of iron tannate, ferrous ferricyanid, and the result of the action of iron on haematein, nigrosin and various other salts whose activities are neutral, held in colloidal solution by the gum arabic.

Heematein is the active coloring matter of logwood and has the empirical formula (O H O it being used before excessive oxidation has rendered it valueless as a col oring matter.

Logwood may be used, in which case heematein is produced by oxidation or fermentation. In this mixture pyroligneous acid oxidizes whatever heemotoxylum there is that changes it to haematein.

It is well known in the art of textile dye ing, that logwood is a mordant dyestutf upon the fiber and that in the dyeing process the haematein of logwood unites with the mordant to form an insoluble metallic or ganic compound which becomes fixed on the fiber. An object of the present invention is to provide a dyeing compound whereby the Specification of Letters Patent.

Patented Nov. 9, 1920.

Application filed December 2, 1919. Serial No. 341,981.

hereinbefore mentioned materials may be colored directly so as to be fast against ordinary washing without mordanting. To this end the composition contains an iron mordant. Copperas of commerce (FetlO,.7I-l,(l) is employed which is a well known mordant used in black and brown textile dyeing. The chemically pure crystals consist of ferrous sulfate and water. The copperas is introduced into the solution to produce the required action and give the color in the solution so that it may be put on; with a sponge or brush and thus dyed directly.

The iron above mentioned, however, also acts upon the tannic acid contained in the nut galls to form as, is well lmown a bluish black compound it being found that aleppo nut galls contain from to 66 per cent. of tannic acid and approximately from 5 to 7 per cent. of gallic acid. Thus, gallotannic acid occurs in gall tannins and has the formula:

When the nut galls are dissolved in hot water with iron salts the gallotannic acid yields a blue black compound, the gallic acid producing no coloration with ferrous salts, but the solution on standing gradually oxidizing to the ferric state and becoming black and depositing an insoluble precipitate. Because of this gradual oxidation the logwood may also be termed a provisional coloring matter to color the material to be dyed, in the interim, until said gradual oxidation in the fiber of the material is completed, which sometimes requires several days. This oxidation into the black ferric compound renders the latter fast against the action of bleaching agents.

Nutgalls are introduced into the solution partly because tannins are distinguished by the fact that they are taken up readily by the animal skin causing it to be tanned, this property making applicants dyeing composition especially applicable to leather and the like.

Further, tannins will combine with basic dyes producing compounds insoluble in water, and when brought together with salts of heavy metals containing a feeble acid (such as acetic acid) a precipitate is formed containing the metal oxid and the tannin. Applicant employs pyroligneous acid to constitute the feeble acid above mentioned.

The gum arabic serves as a binder and as an agent to produce a colloidal solution. The potassium ferricyanid is used to give a soluble blue or a mixture of ferrous ferricyanid and ferrous potassium ferricyanid, in action with the ferrous sulfate. The anilin nigrosin being used for its shading properties.

I claim:

1. A dyeing composition consisting of a solution of one part of gum arabic, two parts of gallee, three parts of ferrous sulfate, nine hundredths of one part potassium ferricyanid, sixty five hundredths of one part of pyroligneous acid, one part of hzematein crystals, six thousandths of one part of anilin nigrosin and sixty-four parts of water.

2. A dyeing compound consisting of a gall tannin, the mordant dyestuff logwood to combine with said tannin to form an insoluble compound, the iron mordant ferrous sulfite to unite with the haematein of the logwood to form an insoluble metallic organic compound, pyroligneous acid to act on said compound to precipitate the tannin thereof and the metal oxid of the acid, and the analin agent nigrosin to produce a colloidal solution of the whole.

In testimony whereof I afiix my signature.

WALTER J. MILLER. 

